Cam operable adjustable snap-action electrical switch



Feb. 1, 1966 o. ASCHWANDEN 3,233,057

CAM OPERABLE ADJUSTABLE SNAP-ACTION ELECTRICAL SWITCH Filed July so, 196s United States Patent O 3,233,657 CAM OPERABLE ADJUSTABLE SNAP-ACT'QN ELECTRICAL SWITCH Oscar Aschwanden, Giebeleich 5, Zurich 11/52, Switzerland Filed July 30, 1963, Ser. No. 298,678 Claims priority, application Austria, Aug. 17, 1962, A 6,659/ 62 1 Claim. (Cl. 20G-67) This invention relates to an electric switch having two contact elements arranged on a switch frame, a contact arm reciprocatable between the contact elements, a spring engaging the contact arm in a lirst pivot point, under the influence of which the contact arm will lie on one or the other contact element, and an operating lever for initiating the switching movement.` The operating lever is rockably supported on the switch frameA by means of a second pivot point, whereby the contact arm and the spring are each associated respectively through Ia third and a fourth pivot point with the operating arm and the switch frame or vice versa.

Through automation, a great need has arisen for controls and switchgears to be as comp-act as possible, for which entire rows of switches are required generally in juxtaposed relation. The most exacting demands as to accuracy of switching on and olf are thereby made in accordance with the rened technique of automation and the range of the switching programs. This again demands high precision of the control block and its individual parts.

While it is now possible to have switches, and especially small switches, built in series with minimum tolerances, in assembling them to switchblocks, there result disadvantages in using switches of the conventional type. If, for instance, the switches are actuated through a series of cam disks arranged on a common shaft, because of the small erecting tolerances the switches will be lat unequal distances yfrom the4 cam disks. Therefore, on account of these yunequal distances, the operating levers on the camdisks are rocked to a greater or lesser extent, which means that theswitches, as actuated by the cam disks, actuate at different moments. The switches as used heretofore have fixed set operating levers, so that the deviations in the moments `for actuating the switches can only be eliminated to a certain extent by restricting the tolerances, which necessitates complicated adjustment and renders erection 'expensive and slower.v It is already known to have thesejxed operating levers provided with regulating means.l The Vdrawback ofthis is that the regulating means are located on a movable part of the switch. It is also known Vto lhave each switch of a switchblock individually and movably supported within a xed frame, but the possibility of regulationis then expensive. Consequently, accurate tuning of all switches united to one switchblock for actuation at the same moment is impossible with simple means.

The primary object of the invention is to create a switch in which, independently on such erecting tolerances, the switching moment has to be determined accurately. Moreover, this switch shall be constructed in such a way that it is above all suitable for arranging these switches side-by-side in rows to form switchblocks.

The switch is characterized in that, in addition to the change in position of the pivot points capable of being effected by the operating lever, at least one of the four pivot points is adjustable by means of a regulating screw for altering the switching moment of the switch in dependence on the movement of the operating lever.

Further features of the invention will appear from the following description and claim taken in conjunction with 3,233,057 Patented Feb. l, 1965 the accompanying drawing wherein there is shown, purely by way of example, one preferred form of embodiment incorporating the invention.

In said annexed drawing:

FIG. 1 is a longitudinal section of an unactuated switch;

FIG. 2 is a side view of the switch according to FIG. l showing another position; and,

FIG. 3 is a top plan view of Athe switch.

The switch comprises three electric terminals 1, 2, 3, these reference numerals designating at the same time the sequence of the electric connections of the switch. The terminals 1, 2, 3 are formed as n-uts and are mounted on the underside of a switch base plate of insulating material, representing the switch frame 4. Terminal 1 is integral with a metal plate 5 which is on the upper side of base 4. Terminal 2 forms one piece together with a lower contact element 6, and terminal 3 also forms one piece together with a bow 7 carrying the upper contact element 8, which are riveted to the switch base plate 4. Plate 5 is turned up at one end and has a prismatic notch 9 therein which serves as a stationary pivot point for a rockable operating lever 10. This latter consists of a metal-strip of the same width as the bow 7. The free extremity of the operating lever 10 is formed for actuation through a cam disk 11 or a slide or the like. For this purpose, the free end of said lever is formed by a special attachable part 10 of a sliding material. When using a metal cam disk or -a slide, said material may consist of an insulating substance. Alternatively, instead of part 12, a roller may be provided. Lever 10 has a longitudinal slot 13 therein which extends into a circular aperture 14. Lever 10 has a prismatic notch 15 which serves as a pivot point for the forked end 17 of a contact arm 16. The contact arm 16 carries a contact 18.

In the switch base plate 4, besides the electric terminal, there is arranged a regulating screw 19 having a pin 20 which, in the direction of rocking of lever 10, projects through the slot 13. At the top, said pin has an adjoining collar 21 which in diameter is larger than the width of slot 13 so as to provide a stop for lever 10 which is rockable about the notch 9 between the switch base plate 4 and collar 21. At the same time, the upper free end of the screw 19 serves as stationary pivot point for a tension-spring 22 with the other end engaging the pivot point 2S of the contact arm 16. Spring 22 presses contact arm 16 into the notch 15, and contact arm 16 together with lever 10 into notch 9. The aperture 14 has a diameter somewhat larger than the collar 21. The switch with its terminals 1, 2, 3 is mounted on a base 23, the surface having a printedcircuit (not shown) on whose conductingcontacts the terminals 1, 2, 3 lie. The switch is mounted on the base 23 by means of screws 24 (one only shown).

`The operation of -the switch is as follows: With the switch unactuated according to FIG. 1, the operating lever 1i) rests on part 29 of the cam disk 11. Thereby notch 15 -lies above the direction o-f action of draw-spring 22. Contact -18 thus rests on contact element 6. With the switch operated according to FIG. 2, the notch 1S lies below the direction of action of the spring 22, and contact 18 rests on contact element 8.

By turning the screw 19 by means of a Screwdriver, the pivot point of spring 22 at screw 19 is altered to the other pivot points 28, 15 and 9. Therefore the characteristics of the switch are changed. If the operating lever 10 of the switch passes over the -part 29 of the cam disk 11, because of erecting tolerances, lies somewhat lower (FIG. l) than another switch of the same switchblock, by adjusting the regula-ting screw `19 of one switch (or of both switches) -it can tbe -achieved that -both switches, operated by such cam disks lil, actuate at the same moment, i.e.

the contacts 1S tilt into another position simultaneously.

But it is also possible that a switch shall actuate after another switch only with a cer-tain delay. Such delay may likewise be determined accurately by setting the screw 19 correspondingly.

By altering the switching moment of the switch, the time, from the commencement of the movement of lever to the tilting of contact 18 into another position, will be changed.

The other pivot point 28, 1S, 9 `may also be adjustable. Most simply, readjustment can be carried out at the stationary pivot points, hence at notch 9 or at screw 19.

As indicated on FIGS. l and 2, the reference characters A and B represent toggle joint members and the line C indicates an action line` with the toggle members in the position shown in FIG. 1 and the ac-tion line D in FIG. 2 shows the toggle members in lthe second position, as to the contact members 6 and 8, together with the mo'valble contact member 18, which is mounted on one of the toggle joint members B. Thus, as to the toggle joint junction, the -action line C in FIG. 1 shows the switch in the position 4in which the contacts 18 andy 6 are in contact with each other and FIG. 2 yshows the Vaction line D for the toggle members with the contacts d8 and 8 in `contact with each other.

The operating lever ylil may have several arms, such as the arm 25 shown in d-ash-dotted lines (FIG. 1) which is to be actuated -by a cam disk 26. These two cam disks 11 and 26 then act on the switch in series-connection.

Screw 19 may have points of engagement at `both ends for screwing it into the switch base plate 4. For this purpose, collar -21 may have a screw-head 27 as shown in dash-dotted line, FIG. l.

Advantageously, Ithe switch in accordance with the invention can be used for printed circuits, in as much as the electric tenminals 1, 2, 3 lformed as nuts lying in one plane are disposed on the switch ibase plate 4, so that the switch with the nuts lies on a base provided with a` printed circuit and may thus be mounted. The electric terminals 1, 2, 3 then serve at the same time for iixing. Thus, in switches known heretofore, the necessary special fixing bores may be dispensed with, whereby the overall length of the switch is shortened.

If a Xing bore at each end of the switch base plate 4 is maintained, all switches can lbe Xed on one common profiled bar o-r the like. The common base 2'3 may then be done away with, and the undersides of the switch form a terminal board'. Thus, the electric conductors are connected direct to the terminals 1, 2 and 3.

Furthermore, a single defective switch can [be replaced without the other switches being thereby influenced in any way, which also minimizes maintenance Work on the switch or control block.

When installing or removing a switch, the operatingV The switch according to the Iinvention has a very low lever 10 rests -on `collar 21 so that the rocking path of height and width. By reason of the special structural design orf ythe switch, the overall width of a switch is sub- 4 J stantially governed by the width of the metal-strip adopted for the operating lever 10. Hence these switches may be built very narrow and can be usedvery well-l in carncontrolled switch'blocks, such sw-itchblocks becoming very compact even with a plurality of juxtaposed switches. Also the height of the switch is very low because of the simple structural design of contact anni I16 and operating lever 10.

By having contact arm 16 lpi'voted to the rockable operating lever 10, the electric Contact elements 6, 8 are self-cleaning, since contact 18 orf contact arm V16 slides first on the respective contact of the stationary contact element 6 or 8, before it rises. Therewith any welding at the contacts are avoided.

Three switches assembled on -a `switchiblock may, for instance, serve as a threephase switch. All `three operating levers 10 are then, for ins-tance actuated iby a single pressure plate. In order that the three switches shall work simultaneously, each switch is adjusted lby means of its screw 19.

Instead of cam disks 11 any known operating members may be provided.

The terminals 1, 2, 3 may also 4be -formed as contact lugs. These are then lodged in the switch ibase plate 4 and are then inserted and lixed in the base 23 which, for instance, has a printed circuit.

What I claim is:

Electric switch comprising a iframe, two spaced contact elements arranged on the frame, a contact arm mounted yto reciprocate between said elements, a tension coil spring connected at one end to said arm andthe other end to the trame at a pivot point thereon so that under the iniluence `olf the spring lsaid arm will abut on one or the other ot said Contact elements, an operating lever for initiating the switching movement and rockably supported on the switch frame at a notch therein and having a pivot point intermediate its ends, said arm being mounted at thel pivot point on the operating lever, a regulatingv screw on the frame which is the pivot .point of the tension coil spring on the frame and is adjustalble toward and away from the rfrarne with at least'one part of the operating lever and the contact arm `@forming the parts of a toggle joint, and the pivot -point of the operating lever on the frame lying outside of an action line of the spring and upon actuating the switch -the pivot point of the operating lever and the` contact arm lying between an action line of the spring and a line of the extended toggle joint- References Cited by the Examiner UNITED STATES PATENTS 2,800,546 7/ 1957 Reitler 200-e67 2,862,083 ll/1958 Bailey 200-67 X 3,015,002 12/1961 Laviana 200--166 X KATHLEEN H. CLAFFY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

